Method for determining the thermal performance of a heat sink

Abstract

A method for determining the thermal resistance constant of a modular heat sink. The method can be carried out by first providing a heat capacity tank formed of a high thermal conductivity metal. A modular heat sink is then mounted on top of the heat capacity tank and heated together with the tank to a temperature of at least 40° C. The heating is then stopped and the heat sink/heat capacity tank is allowed to cool for at least 30 seconds before the temperature and the cooling time of the heat capacity tank is monitored and recorded. The function of dT/dt is then calculated. The amount of heat dissipated is then calculated from the equation of Q=W.Cp.(dT/dt), while the thermal resistance constant is calculated by the equation of R=(T-Tamb)/Q.

What is claimed is:  
     
       1. A method for determining the thermal resistance constant of a thermal module comprising the steps of: 
       providing a heat capacity tank fabricated of a metal;  
       mounting a thermal module on top of said heat capacity tank;  
       heating said heat capacity tank and said thermal module to a temperature of at least 40° C.;  
       stopping said heating step and cooling for at least 30 sec.;  
       monitoring temperature and cooling time of said heat capacity tank for a preset length of time and calculating dT/dt;  
       calculating the amount of heat dissipated by the module from the equation  
       
         
             Q=W·C   p ·( dT/dt )  
         
       
       wherein W and C p  are the weight and the heat capacity of the heat capacity tank, respectively; and  
       calculating the thermal resistance constant of the module from the equation  
       
         
             R= ( T−T   amb )/ Q    
         
       
       wherein T and T amb  are the temperature of the heat capacity tank and the ambient temperature, respectively.  
     
     
       2. A method for determining the thermal resistance constant of a thermal module according to  claim 1 , further comprising the step of stopping said heating step and turning on a forced-air cooling device for a time period of at least 1 min. prior to said monitoring step. 
     
     
       3. A method for determining the thermal resistance constant of a thermal module according to  claim 1 , wherein said heat capacity tank is formed of a metal having a thermal conductivity of at least that of Zn. 
     
     
       4. A method for determining the thermal resistance constant of a thermal module according to  claim 1 , wherein said heat capacity tank is formed of a metal selected from the group consisting of Cu, Al, Au and Zn. 
     
     
       5. A method for determining the thermal resistance constant of a thermal module according to  claim 1 , further comprising the step of providing said heat capacity tank with: 
       heating plates for heating said heat capacity tank;  
       at least one thermocouple for measuring temperature of said heat capacity tank; and  
       a thermal insulating blanket surrounding said heat capacity tank.  
     
     
       6. A method for determining the thermal resistance constant of a thermal module according to  claim 1 , further comprising the step of providing said thermal module as a fin-shaped heat sink. 
     
     
       7. A method for determining the thermal resistance constant of a thermal module according to  claim 1 , further comprising the step of providing said thermal module as a pin-shaped heat sink. 
     
     
       8. A method for determining the thermal resistance constant of a thermal module according to  claim 1 , wherein the thermal module is mounted on top of said heat capacity tank with a thermal conductive layer therein-between. 
     
     
       9. A method for determining the thermal resistance constant of a heat sink comprising the steps of: 
       providing a heat capacity tank fabricated of a metal;  
       mounting a heat sink on top of said heat capacity tank;  
       heating said heat capacity tank and said heat sink to a temperature of at least 40° C.;  
       stopping said heating step and cooling for at least 30 sec.;  
       monitoring temperature and cooling time of said heat capacity tank for a preset length of time and calculating dT/dt;  
       calculating the amount of heat dissipated by the heat sink from the equation  
       
         
             Q=W·C   p ·( dT/dt )  
         
       
       wherein W and C p  are the weight and the heat capacity of the tank, respectively; and  
       calculating the thermal resistance constant of the heat sink from the equation  
       
         
             R =( T−T   amb )/ Q    
         
       
       wherein T and T amb  are the temperature of the heat capacity tank and the ambient temperature, respectively.  
     
     
       10. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , further comprising the step of stopping said heating step and turning on a forced-air cooling device for a time period of at least 1 min. prior to said monitoring step. 
     
     
       11. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , wherein said heat capacity tank is formed of a metal having a thermal conductivity of at least that of Zn. 
     
     
       12. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , wherein said heat capacity tank is formed of a metal selected from the group consisting of Cu, Al, Au and Zn. 
     
     
       13. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , wherein said heat capacity tank is formed of a metal having a heat capacity not higher than that of Zn. 
     
     
       14. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , wherein said preset length of time for said monitoring step is at least 3 min. 
     
     
       15. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , wherein said preset length of time for said monitoring step is between about 3 min and about 10 min. 
     
     
       16. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , further comprising the step of heating said heat capacity tank and said heat sink to a temperature of at least 70° C. 
     
     
       17. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , further comprising the step of heating said heat capacity tank and said heat sink to a temperature of at least 90° C. 
     
     
       18. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , further comprising the step of mounting a heater in said heat capacity tank. 
     
     
       19. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , further comprising the step of mounting an electric heater in said heat capacity tank. 
     
     
       20. A method for determining the thermal resistance constant of a heat sink according to  claim 9 , further comprising the step of flowing an electrical current to said heater in said heat capacity tank.